DOS THE TERTIARY FLORA OF AUSTRALIA, 



not in finding resemblances but in making a selection, as the 

 resemblances are often so numerous. 



Judging from a paper read by Ettingshausen before the Imperial 

 Academy of Vienna in the year 1854,* no one could recognise the 

 difficulties more than that author. In this paper he mentions 

 how attention had been called to the subject of leaf venation 

 two years before by Leopold von Buch at a meeting of the Berlin 

 Academy of Sciences, and regret therein expressed that investi- 

 gation with a view to classification of leaf characters had not 

 been seriously attempted. Ettingshausen points out in his paper 

 the impossibility of carrying out any systematic classification, 

 and he mentions how the forms and venation of Ficus and 

 Vochysia, Cinnamomum and Strychnos, Mertensia and Ceanothus 

 or Zizyphus, Fag us and Dipterocarpus, Salix and certain Lytic- 

 rariece, Jacaranda and Mimosece, Nyssa, Diospyros and Pitto- 

 sporum, Santalum and Sapotacece entirely correspond. On the 

 other hand, he shows how we come across the most heterogeneous 

 types of leaves in one and the same natural order or even the 

 same genus, as for example, in Bignoniaceoe, Saxifrages, 

 Biittneriacece, Euphorbiacece, in Ficus, Sterculia, &c. 



It would appear, therefore, that the matter scarcely calls for 

 any argument seeing that this great authority in fossil leaf naming 

 acknowledged at the outset how utterly unreliable leaf characters 

 were as a guide to classification, and the only wonder is that after 

 the recognition of the impossibility of adopting any system, these 

 sensible conclusions should have been put on one side and the 

 naming of fossil plants from leaves only and often from very 

 badly preserved fragments should have been carried on in such a 

 wholesale manner and with such confidence. 



Ettingshausen has carried out a vast amount of investigation, 

 some of which no doubt is very useful and of great interest, as, 

 for instance, when he attempts to trace back the genealogy of 

 Castanea vesca to C. atavia. This is a kind of work which is 



* On the Euphorbiacece : Sitzungsber. der K. Akad. der Wissensch. 

 Band xii. 



